Low elongation seat belt webbing



y 1967 o. c. H. HUGHES 3,322,163

LOW ELONGATION SEAT BELT WEBBING Filed Feb. 25', 1965 FIG.3.

INVENTOR OSBERT C. H. HUGHES United States Patent 0,

3,322,163 LOW ELONGATION SEAT BELT WEBBING Osbert C. H. Hughes, Hopewell, Va., assignor to Allied Chemical Corporation, New York, N.Y., a corporation of New York Filed Feb. 25, 1965, Ser. No. 435,129 4 Claims. (Cl. 139383) This invention relates to an improved narrow woven fabric webbing of low elongation and good fabric stability.

Fabric webbings employed as safety seat belts are required to have the ability to absorb a high mechanical shock load and to exhibit a fairly low elongation e.g. less than about 18% when subjected to a 2500 lb. tensile test load. In view of their frequent handling during their lifetimeof use, the fabric is also required to have sufficient stability to resist physical degradation under the effects of flexing, folding, and abrasion. Acceptable seat belt webbings have generally been sought by various combinations of yarn and weave. However, it has been found that factors which contribute to the securement of low elongation characteristics generally result in the formation of fabrics lacking adequate fabric stability, a deficiency generally referred to :as sleaziness.

It is therefore an object of this invention to provide a woven fabric belt of low elongation and improved fabric stability. Other objects and advantages will appear hereinafter.

The objects of this invention are accomplished in general by providing a woven fabric having a width between about 1 /2 to 3 inches comprising warp elements spaced about 20 to 66 elements per inch and weft elements spaced at a frequency of between 25% and 70% of the frequency of said warp elements, said warp elements comprising 2 to 5 contiguous strands lying in essentially untwisted juxtaposition, said strands comprised of continuous multifilaments synthetic yarn of .25 to 3.0 turns per inch twist having a tenacity of at least 8 grams per denier and an elongation up to 16%, said warp elements having a denier of at least 1680 and skipping between 20% and 70% of the weft elements in the course of their traversal of the fabric, said weft elements have a denier between 840 and 2,600, and said fabric having an elongation of not above 18% under a tensile load of 2,500 lbs. at room temperature.

Referring to the drawing, FIGURE 1 is a magnified view of a portion of a fabric of this invention showing warp elements passing in the direction of letter B and filling elements, also known as weft elements, passing in the direction of letter A. FIGURE 2 is a sectional elevation taken along lines 2-2 of FIGURE 1 showing a laterally extending weft element having warp elements passing over and under the same in a cord structure. FIGURE 3 is a sectional elevation taken along lines 33 of FIGURE 1. FIGURE 3 shows filling elements disposed on either side of a warp element. In the drawing it is seen that two strands comprise one warp element and that each strand is plied in a cord structure i.e. each strand comprises two yarns.

The woven fabric webbings of this invention can generally be prepared on a narrow gauge loom by essentially standard weaving methods. The warp elements pass through a series of reeds or heddles mounted in a harness which can be controllably raised or lowered by the loom mechanism. By the raising of some harnesses and lowering of others, the fill is brought over some Warp ends and under others and thereby becomes interwoven with the warp ends to form the desired fabric configuration. By means of a predetermined sequence of raising and lowering of the harnesses, and with the cooordinated systematic placement of the weft yarn, the desired fabric structure is obtained. Fabrics of the present invention wherein the warp ends skip between 20% and 70% of opportunities to pass between consecutive weft elements on either side of the fabric can generally be characterized as twill type fabrics. Some specific weaves are known as herringbone twills, sateens, crepes, and fancies.

In the Weaving process for the production of the fabrics of the present invention at least two and as many as five separate strands are brought together without intertwisting or cabling so as to function as a single warp element during weaving. The strands are thus contiguous but readily separable from each other. The strands can consist of either multifilament single yarns, or cords consisting of two or more separate multifilament yarns united by intertwisting. When cords are employed as the strand units of the warp element, the cord twist should be below six turns per inch.

The yarns employed in the warp elements should contain a bundle twist of .25 to 3.0 turns per inch in either S or Z direction. At yarn twist levels below .25 turn per inch the warp elements are found to lack resistance to abrasion, giving rise to processing difiiculties during textile operations and to shortened life expectancy of the belt product. At yarn twist levels above 3 turns per inch, the warp elements become kinky with resultant processing difiiculties, and the belt product is found to have excessively high elongation.

The yarns are preferably made of synthetic polymeric material such as polyamide of the nylon 6 or nylon 6,6 type, polyester, polyolefin, polyacrylonitrile, or mixtures of said polymers, and are generally made to contain stabilizing agents which protect the yarn from degradation by heat, ultraviolet rays, oxidation, and ageing. The cross sectional configuration of the individual filaments of the yarn can be of various shapes for the securement of characteristic aesthetic effects. In order to secure the strength and elongation characteristics of the belts useful as safety belt material of the present invention, the yarns which go into the warp elements must have a tensile strength greater than 8.0 grams per denier and an elongation at the breaking point up to 16%. The yarn components of a strand or warp element can be the same or different, within the above-prescribed requisite characteristics.

In order to secure adequate fabric stability in combination with the low elongation characteristics of the belts of this invention, it has been found necessary for the warp elements to have a total or combined denier of at least 1680. The warp element denier can range as high as 7000 while concordantly diminishing the warp frequency or spacing. It has been found that a warp spacing of :at least 20 elements per inch is required to secure good fabric stability. Below this warp frequency the fabric loses its stability, tending to become selazy in nature. The highest warp count is 66 elements per inch, obtained with elements of low denier. In order to obtain the desired low elongation characteristics of the belt construction, it has been found necessary that the weft elements have a spacing frequency of not more than 70% of the spacing frequency of the warp elements. However, in order to preserve the stability of the fabric, the weft yarn frequency must not be less than 25% of the warp element frequency.

The weft elements can have a denier in the range of 840 to 2520 and are of lower denier than the denier of the warp elements, preferably at least 50% lower. The nature of the fibrous material employed for the weft elements in the practice of this invention is not critical providing said fibrous material possesses adequate strength and durability. Suitable fibrous weft materials thus include cotton, rayon, wool, and yarns of synthetic polymeric materials such as those employed in the warp yarn.

Referring to FIGURES 1, 2 and 3, the paths of the warp elements pass in the direction of letter B and the paths of the filling or weft elements pass in the direction of letter A. In the figure, it is seen that for any given warp element the war element is visible while passing over three weft elements and then passes under two weft elements, the weft elements then being exposed on the face of the fabric whereupon the warp element passes above the next weft element and is visible for the distance of the width of one weft element and passes beneath two successive weft elements to repeat the pattern. This means that in 8 picks or ends of the fabric, the first warp element is on the surface of the fabric for three picks, under for the next two picks, on the surface again for one pick and under for the next two picks. The sequence is repeated indefinitely for this warp element as this chain pattern is used. The warp element is thus seen to skip four opportunities for inter-weaving with the weft yarn in every eight weft yarns, and is thus designated, for the purposes of this invention as skipping 50% of the weft yarn.

It should be noted that fabrics within the scope of the instant invention can vary in their weave and also in the percent of skipping of weft yarns. For the purpose of the present invention the percentage of skipping of weft yarn by the warp element is taken as the average value for all the warp elements of a given fabric.

The elongation of the seat belt webbing of the present invention is measured on an Instron Tensile Tester on belt specimens of 10 length. The percent elongation is measured as the percent increase in the sample length at 2500 pounds force at room temperature.

Example 1 A series of two-inch wide woven belts were made in various fabric designs on a Fletcher narrow fabric loom employing eight harnesses. The number of strands per warp element was varied in the series, however the total number of strands per inch of fabric was maintained constant at 124 throughout the series. The warp strands employed in all belts consisted of two identical nylon 6 multifilament yarns plied together With 1.8 S turns per inch (t.p.i.) cabling. The yarn is 840 denier, 136 filaments, having /2Z t.p.i., a tenacity of 9.4 grams per denier, and an elongation of 15.6% at its breaking point. 840 denier nylon 6 yarns identical with those used in the warp were also employed singly as the weft elements of all belts at a spacing frequency of 16.5 strands per inch. The belts prepared and their properties are presented in Table I. The elongation and breaking strength data were obtained on dyed belts by averaging three tests. Six different fabric pattern designs or. Weave diagrams were utilized in the 7 below samples. The weave diagrams or fabric pattern designs are represented by the below six charts. In the charts X represents a portion of a warp element when the warp is visible at the upper surface of the fabric for a given number of weft elements or picks. Likewise, the weft elements are represented by in those portions between warp elements where they are visible on the same surface of the fabric. For example, in Chart 1, in the first warp element there are three X in a vertical position followed by two 0, an X and two 0 which means that in eight picks or ends of the fabric, the first warp element is on the surface of the fabric for three picks, under the next two picks, on the surface again for one pick and under the next two picks. This sequence is repeated indefinitely for this warp element as long as the chain pattern is used.

CHART 1 1 l 2 t 3 4 l 5 l 6 7 l 8 o o X X o o X X o X o X 0 X X o X X o 0 X X o o o X X o o X o X o o X X o o X X X o X o X o o X X X o o X X o o X o o X X o X 0 CHART 2 o o o X o X o X o o X X o o X X o X o X o o o X X X o o X o o o o X 0 o X X o o o o X o X o X o o o X X o o X X X o X o o o X o X X o o o X o o X o o o X X o o CHART 3 o o X o X 0 X X o X X 0 X 0 o X o X o o X X o X X X o X o X o o X o o X o X X o X o X X o o X o o o X o X o X X o X X o X o o X o X o o X X o X X X o X o X o o X 0 o X o X X o X o X X o o X o CHART 4 o X o X X o o X X 0 X o X o X o o X o X o X X o X o X o X o X o o X X o o X o X X o X o X 0 X o X o 0 X o X o X X o X o X 0 X 0 CHART 5 X o X o o X X o o X X o X o X o o X o X X o o X X X 0 X o X o o X o X X o o X o o o X 0 X o X X o X o o X X o X X o o X o X o X CHART 6 o o X X o o X X o o X o X o X X o X o o X X o X X X o o X X o o X X 0 X o X o o X o X X o o X o o o X X o o X X o o X o X o X X o X o o X X o X X X o o X X o 0 X X o X o X o 0 X o X X o o X 0 The belts of Table I had a weight of about 1.85 ounces per yard, and were found to have good stability, resisting fabric deterioration with repeated bending, flexing and folding.

The data demonstrate in general the effects of the significant parameters of this invention, such as warp element ments of this invention.

For purposes of comparison, a belt of similar construction to sample A4 was made, except that, instead of warp elements comprising two strands, each consisting of two 840 denier yarns, a single yarn of 3360 denier, 2.5 t.p.i., was employed. The resultant belt had an elongation of 20%, which is above the acceptable limit of 18%.

In a control experiment, a plain square weave fabric belt was prepared employing the Warp elements and percent fill spacing of sample C4. The resultant belt, having a percent skipping of weft picks by warp elements of was found to have an elongation of 20.5%.

In a separate experiment, a belt similar to D3 was prepared except that the warp elements were made to consist of six separate strands instead of five. The belt obtained was found to have an acceptable elongation but was sleazy.

TAB LE I Number P er of Strands mn g 0f Weft Elonga- Breaking Sample 1 per Warp Weft PICKS Spacing 2 tion 3 Strentgh 4 Element y p Elements 2 50 26. 6 12. 8 6, 180 2 60 26. 6 10. 7 6, 530 2 66. 5 26. 6 10. 2 6, 540 2 25 26. 6 11. 9 6, 017 2 50 26. 6 11. 8 6, 233 2 66. 5 26. 6 10. 0 6, 437 3 50 40. 0 10. 7 6, 057 3 60 40. O 9. 8 6, 343 3 66. 5 40. 0 9. 8 6, 547 3 25 40. 0 12. 7 5, 920 3 50 40. U 11. 9 6, 277 3 66. 5 40. 0 10. 6 6, 357 4 50 53. 3 1D. 4 6, 360 4 60 53. 3 10. 0 6, 480 4 66. 5 53. 3 11. 2 6, 393 4 25 53. 3 12. 4 5, 937 4 50 53. 3 13. 1 6, 233 4 66. 5 53. 3 11. 0 6, 390 5 66. 5 66. 5 11. 5 6, 440

1 Identical numerals in the sample number represent identical fabric pattern designs or weave diagrams.

2 Expressed as percent of the warp element fzequency.

2 Percent extension of belt at a load of 2,500 lbs. at room temperature.

4 Expressed in pounds force.

Example 2 In order to study the effect of warp yarn twist on fabric properties, a series of 2 inch wide woven belts were made on a Fletcher narrow fabric loom employing for the warp elements three 840 denier, 136 filament polyethylene terephthalate twisted yarns of 8.5 grams per denier tenacity and 14.5% elongation. The individual warp yarns were consolidated into single warp elements by drawing them through the same heddle on the loom. The weft elements were 1100/980 Tyrex rayon. The warp elements were spaced 66 per inch and the weft yarn was spaced 15 per inch. The weaving pattern is a 2 x 2 twill. In the several fabrics made, the degree of twist of the warp yarns was varied although each of the 3 yarns had the same twist. The samples made, and their properties are presented in Table II.

TABLE II Twist (Turns per Inch) Elongation Remarks Too soft-not acceptable. Acceptable.

Do. Good.

Do. Not acceptable.

HHH

O'SCJIOOCHD From the foregoing it is readily seen that I have provided a new and useful fabric particularly suitable as seat belt webbing. The fabric of this invention has an elongation well below the recommended maximum of 18% under a tensile load of 2,500 lbs. determined at room temperature. Hence, users of the safety belts employing the seat belt webbing of fabric of this invention are not put to the jeopardy of elongation of seat belt Webbing due to force thereon, occasioned by the quick impact caused by automobiles and the like stopping short. Other advantages of the invention are apparent to those in the art.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but it is rec ognized that various modifications are possible within the scope of the invention claimed.

I claim:

1. A woven fabric having a width between about 1 /2 to 3 inches comprising warp elements spaced about 20 to 66 per inch and weft elements spaced at a frequency of between 25% and 70% of the frequency of said warp elements, said warp elements comprising 2 to 5 contiguous strands lying in essentially untwisted juxtaposition, said strand comprised of continuous multifilament synthetic yarn of .25 to 3.0 turns per inch twist having a tenacity of at least 8 grams per denier and an elongation up to 16%, said warp elements having a denier of at least 1680 and skipping between 20% and 70% of the weft elements in the course of their traversal of the fabric, said weft elements having a denier between 840 and 2600, and said fabric having an elongation of not above 18% under a tensile load of 2500 pounds.

2. The fabric of claim 1 wherein said warp elements skip at least 50% of said weft elements.

3. The fabric of claim 1 wherein said strands consist of a plurality of twisted multifilament yarns plied in a cord structure.

4. The fabric of claim 1 wherein the denier of said weft elements is not more than 50% of the denier of said warp elements.

References Cited UNITED STATES PATENTS 2,619,705 12/1952 Foster 139420 X 2,639,852 5/1953 Sanders et a1. 280- 2,788,023 4/ 1957 Renand 139420 X 2,956,331 10/ 1960 Whitehead 139420 X FOREIGN PATENTS 1,301,342 7/1962 France. 1,359,036 3/1963 France. 1,350,537 12/ 1963 France. 1,180,689 10/1964 Germany.

777,567 6/1957 Great Britain.

848,005 9/ 1960 Great Britain.

906,976 9/ 1962 Great Britain.

939,705 10/ 1963 Great Britain.

947,661 1/ 1964 Great Britain.

954,586 4/1964 Great Britain.

100,839 11/1962 Norway.

OTHER REFERENCES Federal Specification Belt; Seat Passenger Type, Automotive, January 19, 1960, JJ-B-a.

Man-Made Textile Encyclopedia, Textile Book Publishers, Inc., New York, N.Y., copyright 1959, pp. 326- 327copy in group 360.

Textile Industries, vol. 126, No. 8, August 1962, W. R. C. Smith Publishing Co., Atlanta, Ga., p. 27, copy in group 360.

MERVIN STEIN, Primary Examiner.

J. KEE CHI, Assistant Examiner. 

1. A WOVEN FABRIC HAVING A WIDTH BETWEEN ABOUT 1 1/2 TO 3 INCHES COMPRISING WARP ELEMENTS SPACED ABOUT 20 TO 66 PER INCH AND WEFT ELEMENTS SPACED ATA A FREQUENCY OF BETWEEN 25% AND 70% OF THE FREQUENCY OFSAID WARP ELEMENTS, SAID WARP ELEMENTS COMPRISING 2 TO 5 CONTIGUOUS STRANDS LYING IN ESSENTIALLY UNTWISTED JUXTAPOSITION, SAID YARN OF .25 TO 3.0 TURNS PER INCH TWIST HAVING A TENACITY OF AT LEAST 8 GRAMS PER DENIER AND AN ELONGATION UP TO 16%, SAID WARP ELEMENTS HAVING A DENIER OF AT LEAST 1680 AND SKIPPING BETWEEN 20% AND 70% OF THE WEFT ELEMENTS IN THE COURSE OF THEIR TRAVERSAL OF THE FABRIC, SAID WEFT ELEMENTS HAVING A DENIER BETWEEN 840 AND 2600, AND SAID FABRIC HAVING AN ELONGATION OF NOT ABOVE 18% UNDER A TENSILE LOAD OF 2500 POUNDS. 